Images show a fire erupting on at least two carriages of a train on the Kerch bridge alongside collapsed road sections. Witnesses said the explosion took place around 6 a-m local time on Saturday and said it could be heard from miles away.
At least three people have been killed.
Kyiv has not claimed responsibility for the incident but a Ukrainian presidential advisor tweeted an image of the flames and said: “Crimea, the bridge, the beginning. Everything illegal must be destroyed, everything stolen must be returned to Ukraine, everything occupied by Russia must be expelled.”
For Ukrainians, the crossing opened in 20-18 is a hated symbol of Russia’s annexation of the Crimean Peninsula and is a key supply route for Vladimir Putin’s troops.